---
title: "Animals Around Us"
book: "Primary & Middle School Biology"
subject: biology
language: en
chapter: 2
exercises: 10
source: https://one-course.com/books/biology/1/en/chapter/2-animals-around-us
---

# Chapter 2 — Animals Around Us

A blackbird hops across the lawn, a cat watches it from the wall, an ant carries a crumb bigger than itself along the doorstep. [Animals](#def-g1-animals-around-us-animal) are everywhere around us — in the garden, in the park, in the house. Let us learn to look at them the way a biologist does: at their bodies, and at the way they move.

## 2.1 What is an animal?

**Definition 2.1 (Animal).**

An *animal* is a [living thing](https://one-course.com/books/biology/1/en/chapter/1-living-or-not-living#def-g1-living-or-not-living) that feeds by eating other [living things](https://one-course.com/books/biology/1/en/chapter/1-living-or-not-living#def-g1-living-or-not-living) — plants, or other animals — and that can usually move about on its own. A cat, a blackbird, a fish and an ant are all animals. We are animals too.

**Example 2.2 (Animals of one garden).**

One small garden can be home to many [animals](#def-g1-animals-around-us-animal): a blackbird pulling a worm out of the ground, the worm itself, a snail on a leaf, a spider in its web, a bee in a flower, and the neighbor’s cat. Big or tiny, they all feed and they all move.

![The garden at work: a blackbird pulling its breakfast out of the lawn.](https://one-course.com/images/onecourse/chapters/biology-1/g1-animals-around-us/img-72045144509e.jpg)

*The garden at work: a blackbird pulling its breakfast out of the lawn.*

**Remark 2.3 (Small does not mean unimportant).**

An ant is an [animal](#def-g1-animals-around-us-animal) just as much as an elephant is. Body size does not decide who is an [animal](#def-g1-animals-around-us-animal): eating and moving do. Some of the most amazing [animals](#def-g1-animals-around-us-animal) around us are the tiniest ones.

## 2.2 The parts of an animal’s body

**Definition 2.4 (Parts of the body).**

Most [animals](#def-g1-animals-around-us-animal) have a *head* (with the mouth and most sense organs), a body, and *limbs* — legs, wings or fins — that they use to move. Many also have a *tail*.

![The parts of a cat’s body: head, body, four legs, tail.](https://one-course.com/images/onecourse/chapters/biology-1/g1-animals-around-us/fig-87a88886d582.svg)

*The parts of a cat’s body: head, body, four legs, tail.*

**Example 2.5 (Count the legs).**

Legs come in numbers worth counting. The blackbird walks on $2$ legs, the cat on $4$, the ladybug on $6$, the spider on $8$ — and the earthworm and the snail have no legs at all, yet they still get where they are going.

**Definition 2.6 (Body covering).**

The body of an [animal](#def-g1-animals-around-us-animal) is protected by a covering: *fur* (hair) on the cat, *feathers* on the blackbird, *scales* on the fish, a *shell* on the snail, and smooth wet *skin* on the frog.

**Example 2.7 (Who wears what).**

Stroke a cat: [fur](#def-g1-animals-around-us-covering). Pick up a fallen blackbird [feather](#def-g1-animals-around-us-covering): light and soft. Look closely at a fish at the market: rows of shiny scales, like tiny roof tiles. Three [animals](#def-g1-animals-around-us-animal), three different coats.

## 2.3 How animals move

**Proposition 2.8 (Ways of moving).**

[Animals](#def-g1-animals-around-us-animal) move in ways that match their [limbs](#def-g1-animals-around-us-parts):

- [animals](#def-g1-animals-around-us-animal) with legs *walk* , run, hop or crawl — the cat, the blackbird on the lawn, the ant;
- [animals](#def-g1-animals-around-us-animal) with wings *fly* — the blackbird, the bee, the butterfly;
- [animals](#def-g1-animals-around-us-animal) with fins *swim* — the fish;
- [animals](#def-g1-animals-around-us-animal) with no [limbs](#def-g1-animals-around-us-parts) slide or wriggle — the snail on its one soft foot, the earthworm stretching and shortening.

**Proof.** *Admitted at this level.* ∎

![Limbs and movement go together — and the blackbird appears twice: legs for the lawn, wings for the air.](https://one-course.com/images/onecourse/chapters/biology-1/g1-animals-around-us/fig-7271c5be0d59.svg)

*[Limbs](#def-g1-animals-around-us-parts) and movement go together — and the blackbird appears twice: legs for the lawn, wings for the air.*

**Remark 2.9 (One animal, several ways).**

Many [animals](#def-g1-animals-around-us-animal) have more than one way of moving. The blackbird walks *and* flies; the frog swims *and* hops; the duck walks, swims *and* flies. Watch an [animal](#def-g1-animals-around-us-animal) for a while before deciding how it moves.

**Method 2.10 (Observing an animal).**

To describe an [animal](#def-g1-animals-around-us-animal) like a biologist:

1. look at the parts: head, body, [limbs](#def-g1-animals-around-us-parts) , tail;
2. count the legs, without guessing;
3. name the covering: [fur](#def-g1-animals-around-us-covering) , [feathers](#def-g1-animals-around-us-covering) , scales, [shell](#def-g1-animals-around-us-covering) , [skin](#def-g1-animals-around-us-covering) ;
4. watch how it moves: walk, hop, fly, swim, slide;
5. say where you found it: lawn, tree, pond, under a stone.

Never hurt the [animal](#def-g1-animals-around-us-animal): watch, then let it go on its way.

## 2.4 Exercises

**Exercise 2.1 ★.**

Name the four main parts of the cat’s body in the figure. Which part carries the eyes and the mouth?

**Solution of Exercise 2.1.**

Head, body, legs ([limbs](#def-g1-animals-around-us-parts)), tail. The head carries the eyes and the mouth.

**Exercise 2.2 ★.**

How many legs: (a) a hen? (b) a dog? (c) a ladybug? (d) a spider? (e) an earthworm?

**Solution of Exercise 2.2.**

(a) $2$; (b) $4$; (c) $6$; (d) $8$; (e) none — the earthworm has no legs at all.

**Exercise 2.3 ★.**

Give the covering of each [animal](#def-g1-animals-around-us-animal): a sheep, a duck, a trout, a snail.

**Solution of Exercise 2.3.**

The sheep: wool, which is thick [fur](#def-g1-animals-around-us-covering). The duck: [feathers](#def-g1-animals-around-us-covering). The trout: scales. The snail: a [shell](#def-g1-animals-around-us-covering) (over a soft, moist body).

**Exercise 2.4 ★.**

Which [animals](#def-g1-animals-around-us-animal) of this chapter can fly? What do they all have, instead of front legs or arms?

**Solution of Exercise 2.4.**

The blackbird, the bee and the butterfly. They all have wings.

**Exercise 2.5 ★.**

The snail and the earthworm have no legs. How does each of them move?

**Solution of Exercise 2.5.**

The snail slides slowly on its one soft foot, leaving a trail of slime. The earthworm wriggles: it stretches long and thin, then pulls itself short again, and moves forward bit by bit.

**Exercise 2.6 ★.**

A duck can move in three ways. Name them, and say which part of its body it uses for each.

**Solution of Exercise 2.6.**

It walks on its legs, it swims with its webbed feet (its legs again, with toes joined by [skin](#def-g1-animals-around-us-covering)), and it flies with its wings.

**Exercise 2.7 ★.**

Why is an ant an [animal](#def-g1-animals-around-us-animal), by [Definition 2.1](#def-g1-animals-around-us-animal)? Answer with the two ideas of the definition.

**Solution of Exercise 2.7.**

The ant feeds by eating other [living things](https://one-course.com/books/biology/1/en/chapter/1-living-or-not-living#def-g1-living-or-not-living) (crumbs of food, seeds, tiny [animals](#def-g1-animals-around-us-animal)), and it moves about on its own six legs. Feeding and moving: both parts of the definition fit.

**Exercise 2.8 ★.**

Try it: watch one [animal](#def-g1-animals-around-us-animal) outside for a little while — a bird, an insect, a snail. Describe it with the five steps of [Method 2.10](#met-g1-animals-around-us-observe).

**Solution of Exercise 2.8.**

Open answer. A good description names the parts seen, gives a real leg count, the covering, the way of moving, and the place — for example: “a snail on the wall: head with two tentacles, soft body, no legs, a brown [shell](#def-g1-animals-around-us-covering), it slides; found after the rain.”

**Exercise 2.9 ★★.**

A friend says: “Fish cannot be [animals](#def-g1-animals-around-us-animal) — they do not walk!” What would you answer? Use [Proposition 2.8](#prop-g1-animals-around-us-moving).

**Solution of Exercise 2.9.**

Walking is only one way of moving. Fish have fins and swim — that is their way. An [animal](#def-g1-animals-around-us-animal) must feed and move, not walk: the fish does both, so it is an [animal](#def-g1-animals-around-us-animal).

**Exercise 2.10 ★★.**

Mystery [animal](#def-g1-animals-around-us-animal): it has $2$ legs, $2$ wings, [feathers](#def-g1-animals-around-us-covering), and it cannot fly, but it runs very fast. Is it a bird? Could it be the fastest runner of your neighborhood? (Think of an ostrich.)

**Solution of Exercise 2.10.**

Yes, it is a bird: [feathers](#def-g1-animals-around-us-covering) and wings are the give-away, even without flight. The ostrich cannot fly but runs faster than any person — being a bird is about the body, not about flying.